Texturing method

ABSTRACT

There is put forward a method for texturing thermoplastic yarns with which the thread before the provision of texture is brought to the necessary texturing temperature (T 2 ) and during the actual texturing provision is cooled to a setting temperature (T 23 ). The heating to the texturing temperature (T 2 ) is effected in two steps. The actual texturing line ( 24 ) is provided with an active cooling, by which means the yarn is actively cooled to a setting temperature.

The invention relates to a method for texturing a thermoplastic yarn,according to the preamble of the independent patent claim.

According to the newest method introduced onto the market athermoplastic filament is removed from a roll overhead and by a deliverydevice is led to a heating box. The thread runs through a heating box,followed by a false twist unit, to a delivery device. The twist producedby the false twist unit after reaching the optimal plasticity effects aspiral-shaped deformation of the filament which subsequently is set bycooling, connected to the false twist unit the thread provided with atexture without twist via a thread detector reaches the winder andsubsequently via an oiling device reaches the bobbin winder where thetexturised thread is wound.

This method has the disadvantage that it requires a very long processingline which creates a texturing device with a very large constructionallength and a complicated running course of the thread. Accordingly theprocessing speed is limited. This is amongst other things dependent onthe speed and the quality of the heat provision into the thread withinthe heating box. So that the thread may be heated well and uniformly itmust be within the heating box for a long time. This is achieved by thelarge constructional length of the heating box.

With the method according to the invention the processing speed is to bedecisively increased.

An advantage of the invention lies in the fact that with the new methodit is possible to construct a texturing device which is considerablyless long and thus requires considerably less space.

An additional advantage lies in the fact that it is just because of thedecisively shorter constructional manner that considerably largerrun-through speeds may be reached.

A further advantage lies in the fact that one may have an influence onthe specific properties of the thread.

The method according to the invention is hereinafter described incombination with the drawings.

FIG. 1 shows the principle arrangement of the elements which makepossible the new texturing method,

FIG. 2 a special arrangement of the active cooling and

FIG. 3 a further embodiment of the active cooling.

Raw yarn which is to be texturised, for example a thermoplasticfilament, according to the conventional manner is brought onto spools11, 11′ to a loading station 1. From the feed station the raw yarn,normally wound off from the top, gets directly into a texturing module2. After leaving the texturing module the completed texturised yarn isled to a winder station 4 where it is wound up. Between the texturingmodule 2 and the winder station 4 there may be arranged an oiling device3.

The texturing module neither comprises a heating channel nor a purefeeding unit. These necessary functions are assumed by elements withother functions. The raw yarn in the texturing module 2 is firstly woundup at an input speed and heated to a preheat temperature T1.Subsequently the now pre-heated raw yarn is pre-drafted by a certainamount and then heated to the full texturing temperature T2. Thecompletely heated yarn now obtains the texture in a cooled texturingline between a twist stop and a false twist organ. During therun-through through the texturing line the yarn is cooled to the settingtemperature T3. Then the now texturised yarn reaches an elasticitycorrection station which brings the yarn to a selectable correctiontemperature T4. Thereupon the texturised yarn leaves the texturingmodule 2. It is supplied via the oiling device 3 to the winding station4.

Decisive with this method is the two-step heating with a pre-drawingwhich is effected between these steps. This ensures an optimal heatingof the raw yarn in its complete cross section and with all its filamentsto the required texturing temperature T2. The texture by way of this isnot incorporated during the heating but into a yarn which has therequired temperature T2 already in its whole material. Thus in thetexturing region already the setting of the texture in the yarn may becarried out in that in this texturing region the yarn is set already byactive cooling to the setting temperature T3. The supply of the textureindeed is effected from the false twist organ running backwards to thetwist stop and thus chiefly in the vicinity of the twist stop. Thus byway of the cooling, the setting of the texture is effected immediatelywithout the material which has softened by the heat being mechanicallyloaded even further. The advantages of this method are evident and lieon the one hand in the significantly smaller constructional manner of atexturing device for texturing machines and on the other hand in theimproved quality of the obtained texture thread.

An individual texturing device or texturing module 2 may now for examplebe constructed as is described in the following. At the input into thetexturing module 2 the raw yarn reaches a first heating galette 21 whichruns with a circumferential speed V1. This is wound round several times.With this the raw yarn is pulled flat on the surface of the firstheating galette 21 and heated to the preheat temperature T1. In the caseof the texturing of polypropylene the first heating galette 21 ishowever not heated, this means that it is sufficient for it to haveroughly room temperature. These preheat temperatures T1 then permit thepre-drafting or the predrawing with the transfer to a second heatinggalette 22 which runs at a larger circumferential speed V2. Also thesecond heating galette 22 is wound round several times so that thematerial of the yarn is completely heated to the texturing temeratureT2. Via a twist stop 23 the yarn goes through the texturing region 24which is provided with a cooling line. The cooling line has near to thefalse twist unit 25 a lower temperature than at its run-in near to thetwist stop 23. The cooling line brings the yarn at the end of theprovision of the texture onto the yarn to the setting temperature T3, bywhich means the texture in the yarn is set. As a false twist unit 25particularly suitable is a friction twist provider with a plurality offriction disks. Behind the false twist unit 25 then the texturised andtwist-free yarn is pulled from a third heating galette 26 andtransported further. After the third heating galette 26 there may bearranged further method zones. For example after the re-setting afurther heater with a subsequent feeding unit may be applied. With thisbetween the texturing and re-setting there may be incorporated aninterlacing and folding process. Via a usual oiling device 3 the yarnreaches the winding station 4. With the third heating galette 26 thetexturised yarn may in any case be heated so much until the elasticityin the yarn is reduced to a desired amount.

Likewise decisive is the active cooling during the texturing line 24.Likewise the cooling must be of a sufficient strength and able to betransferred to the yarn, wherein one must take particular considerationthat the yarn during the whole production speed during the texturing iscooled to the necessary temperatures. For this not only is an aircooling suitable but also a fluid cooling with and without directcontact with the yarn. Further special possibilities are likewiseprovided so that the heat existing in the heated yarn may also besufficiently removed by the cooling line. For example such a coolingchannel may be filled or flushed with water, oil, coolant or liquidsodium or salt-containing medium, with a salt or salt mixture with asuitable melting temperature. Particularly suitable is of course the useof a coolant which vapourises in the prevailing temperature range ofbetween roughly 50° and 300° C. At the same time the latent heatrespectively the arising vapourisation cold considerably helps the yarnto lose sufficient heat in order to cool it to a suitable temperaturewithin the texturing line 44. The cooling line may be provided with acooling rail, a cooling channel, a cooling tube or likewise whose lengthmay be adjusted for the purpose of optimisation. It is clear that thecooling rail must contain material with a good heat conductibility sothat the heat removed from the yarn may also be transported way. Itshould also produce little friction and simultaneously be chemicallystable.

In the variant as is shown in FIG. 2, at the beginning of the texturingline 24 there is arranged a spray unit 242. Here during the texturingprocess for example water is sprayed with the smallest droplets onto theyarn. These small droplets cool the yarn in that on vapourising theyremove heat from the yarn. So that there remains no undesired residualdampness in the yarn, at the end of the active cooling line, thusshortly before the false twist organ 25 there may be applied a vacuum orarranged a suction chamber. By way of the vacuum the last part ofsprayed on water vapourises or evaporates. Such a cooling with a directyarn contact and a medium which removes much latent heat is of courseparticularly effective.

In a variant according to FIG. 3 there is shown an active air cooling.The texturing line comprises a cooling rail which is provided with anumber of air nozzles 243. Cooling air, particularly also precooled airis via feed conduits 2431 blown to the air nozzles 243 and subsequentlyimpinges the yarn F which is moved in the direction of the arrow throughthe cooling rail. Particularly suitable is an arrangement of an airnozzle 2432 which is arranged at an angle inclined to the runningdirection of the yarn and specifically against the running direction sothat the air is blown from the colder part to the warmer part. Of coursesuch air nozzles may be combined in a varying arrangement. Likewiseblowing nozzles 234 may be combined with suctionings so that thethroughput of air and thus the efficiency of the cooling of the yarn isoptimised.

In FIG. 3 the cooling rail is also shown in a particularly suitableform. With this it is open laterally. This permits the device for thetexturing method according to the invention to be provided with anautomatic charging device. A robot arm with a suction pistol mayautomatically thread up a filament to be texturised. All elements of thetexturing device are freely accessible from the side so that the robotarm may automatically pass through all stations.

By way of an additional arrangment of sensors for measuring the threadtemperature and its on-line evaluation the heating and cooling may becontrolled in an optimised manner to the texturing speed and to the typeof the yarn to be texturised. Likewise a thread tension control withmeasurement and regulation may be important. For this a sensor formonitoring the thread tension is arranged in the region of the texturingline 24 and its readings are used for the control of the thread tension.By way of the mentioned control of the thread tension in the texturingregion, a ballooning, i.e. oscillation of the yarn may at least bepartly supressed respectively prevented. This is also possible by way ofa particular design of the cooling line. For example the cooling channelmay have a narrow free cross section or the yarn may be pulled over acooling tube.

A texturing machine thus consists of a plurality of such texturingdevices which each individually may be operated in an optimised manner.By way of this the flexibility of the texturing and the quality may beincreased. With the multi-stage and individually controllable preheatingand pre-drawing, combined with the active cooling in the texturing line,there results a decisively smaller construction of texturing machinesthan is possible today.

What is claimed is:
 1. A method for the continuous texturing of athermoplastic yarn amid the supply of heat, characterised in that a yarnpulled from a roll is first brought to a pre-heat temperature (T1),whereupon the pre-heated yarn is pre-drawn and after the pre-drawing isheated to a texturing temperature (T2), whereupon the, yarn on atexturing line between a twist stop and a false twist organ is providedwith texture amid simultaneous cooling of the yarn to a fixationtemperature (T3), and whereupon the texturised and set yarn issubsequently transported away with a pull-off.
 2. A method according toclaim 1, characterised in that the heating to the texturing temperature(T2) is effected in two steps.
 3. A method according top claim 1,characterised in that subsequent to the texturing line there is effecteda reduction in elasticity.
 4. A method according to claim 1,characterised in that in the region of the texturing line the actualthread temperature is measured and its readings are used for the controlof the pre-heating and the active cooling.
 5. A device for thecontinuous texturing of a thermoplastic yarn amid the supply of heatwith a yarn run-in and a yarn run-out and with a texturing line betweena twist stop and a false twist organ, wherein the texturing line runsthrough a cooling channel, characterised in that between the yarn run-inand the twist stop there is present a two-stage heating, which comprisesa first heating galette and a second heating galette, wherein the secondheating galette comprises a higher temperature than the first heatinggalette and that the cooling channel is provided with an active cooling.6. A device according to claim 5, characterised in that the false twistorgan comprises a multitude of twist providing disks.
 7. A deviceaccording to claim 5, characterised in that between the false twistorgan and the yarn run-out there is arranged a third heating galette. 8.A device according to claim 5, characterised in that the rotary speedsand temperatures of the first, second and third heating galette arecontrollable.
 9. A device according to claim 5, characterised in thatthe active cooling is an air cooling and comprises at least one airnozzle.
 10. A device according to claim 9, characterised in that the airnozzle is an air nozzle which is inclined with respect to the runningdirection of the thread.
 11. A device according to claim 5,characterised in that the active cooling is a fluid cooling andcomprises a spray unit for spraying fluid onto the yarn.
 12. A deviceaccording to claim 11, characterised in that the active coolingcomprises a suction chamber for suctioning residual dampness from theyarn.
 13. A device according to claim 5, characterised in that thecooling channel is open on one side.
 14. A device according to claim 5,characterised in that there are arranged sensors for measuring thethread temperature in the region of the cooling channel.
 15. A deviceaccording to claim 6, characterised in that the rotary speeds andtemperatures of the first, secondhand third heating galette arecontrollable and the air nozzle is an air nozzle which is inclined withrespect to the running direction of the thread.
 16. A device accordingto claim 12, characterised in that the cooling channel is open on oneside.